Method and arrangement for entering a preceding vehicle autonomous following mode

ABSTRACT

A method for entering a preceding vehicle autonomous following mode includes the steps of registering and identifying at least one preceding vehicle in front of a host vehicle by at least a first and a second sensor device, comparing the preceding vehicle with vehicle data in a remote database system, and upon a match establishing a communication channel between the preceding vehicle and the host vehicle, identifying to an operator of the host vehicle preceding vehicles with which the communication channel has been established, and obtaining from the operator a selection of a target vehicles to engage following of. Finally, autonomous following mode of the target vehicle is engaged, wherein a vehicle control system automatically controls at least the following three main functions of the host vehicle: forward propulsion, steering, and braking.

BACKGROUND AND SUMMARY

The present invention relates to a method for entering a precedingvehicle autonomous following mode, and an arrangement for entering andoperating a preceding vehicle autonomous following mode.

Adaptive vehicle cruise control systems for maintaining a set speed ofthe vehicle, and to adapt the vehicle speed upon approaching a slowervehicle from behind are well-known. Such adaptive systems however onlyto a snail extent reduce risk of collision, reduce fuel consumption andincreases driver comfort.

Document US 2007/0083318 A1 discloses a method and system to controlforward movement of a vehicle, where a preceding target vehicle isautomatically followed. The system involves a dedicated short-rangecommunications (DSRC) protocol for communicating with the precedingvehicle, forward looking sensors, and control of engine and braking whenthe system operates in an automatic following routine.

The problems with the solution according to the prior art are thatdriver comfort is low due to the partial restriction of driverresponsibility, and that communication between the vehicles isrestricted to ad-hoc dedicated short-range communication, which can bedifficult to manage and deploy, and lack of necessary communicationreliability.

There is thus a need for an improved method and arrangement for enteringpreceding vehicle autonomous following mode that removes the abovementioned disadvantages,

It is desirable to provide a method and arrangement for entering andoperating a preceding vehicle autonomous following mode, where thepreviously mentioned problems are partly avoided.

According to an aspect of the invention, a method is provided comprisingthe steps of registering at least one preceding vehicle in front of ahost vehicle by means of at least a first and a second sensor device,identifying said at least one preceding vehicle, comparing said at leastone preceding vehicle with vehicle data in a remote database system, andupon match establishing a communication channel between said at leastone preceding vehicle and said host vehicle, identifying to an operatorof said host vehicle preceding vehicles with which said communicationchannel has been established, obtaining from said operator of said hostvehicle a selection of a target vehicle to engage following of, andengaging autonomous following mode of said target vehicle, wherein avehicle control system automatically controls at least the followingthree main functions of said host vehicle: forward speed, steering, andbraking.

According to another aspect of the invention, an arrangement is providedcomprising at least a first and a second sensor device for registeringat least one preceding vehicle in front of a host vehicle, a vehiclecontrol system for identifying said at least one preceding vehicle, aremote database system comprising vehicle data with which said at leastone preceding vehicle is compared, such that a communication channel isestablished upon match between said at least one preceding vehicle andsaid host vehicle, an identifying device with which preceding vehicleswith which said communication channel has been established areidentified to an operator of said host vehicle, obtaining, part forobtaining from said operator a selection of a target vehicle to engagefollowing of, and a vehicle control system which controls at least thefollowing three main functions of said host vehicle: forward speed,steering, and braking, for operation said host vehicle in an autonomousfollowing mode.

By comparing the identity of the preceding vehicle with vehicle data ina remote database system, and upon match establishing a communicationchannel between the preceding vehicle and the host vehicle,establishment of initial vehicle to vehicle communication is simplified,communication can be established by means of any desired communicationprotocol, deployment and upgrades are managed centrally, vehiclesincluded the database system can be better controlled and observed,services may be provided to the members of the database system via thecommunication channel, and wireless communication unification isassured. Hence, a more reliable and secure communication is achievedthat is easy to manage and upgrade.

Furthermore, the vehicle control system automatically controls all threemain functions of said host vehicle, namely forward speed, steering, andbraking for improved driver comfort and increased safety. Depending onthe latency in communication between proceeding vehicle and hostvehicle, the range gap between said vehicles can be reduced to a fewmetres, thus leading to significant reduction of fuel consumption

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail below with referenceto a preferred embodiment shown in the drawings, in which

FIG. 1 shows an arrangement for entering and operating a precedingvehicle autonomous following mode according to the invention;

FIG. 2 shows a digital screen displaying an image of ahead of the hostvehicle according to the invention.

DETAILED DESCRIPTION

In the following a preferred embodiment of the invention is shown anddescribed, simply by way of illustration of one mode of carrying out theinvention,

FIG. 1 shows a schematic view of the inventive arrangement for enteringand operating a preceding vehicle autonomous following mode comprising ahost vehicle 2, a preceding vehicle 1 and a remote database system 5.The preceding vehicle 1 is preferably a motor vehicle, such as anautomobile, bus, or truck driving forward on a road.

The host vehicle 2 comprises an operator 6 driving the host vehicle 2,and vehicle control system 10 for engaging and operating the precedingvehicle autonomous following mode. For this purpose, the vehicle controlsystem 10 receives information about preceding vehicles 1, such asposition, speed, type, and identification from first and second sensordevices 3, 4 arranged in the front region of the host vehicle 2.

The first sensor device 3 is an image sensor adapted for objectdetection and identification, preferably by detecting light from thevisible or IR spectrum. The image sensor is preferably used incombination with a digital screen 16 arranged in the cockpit of the hostvehicle 2, displaying a real-time image of ahead of the host vehicle 2.The image sensor is preferably also used for identification of a licenseplate of the preceding vehicle 1, as well as for determining type ofpreceding vehicle 1 driving lane used by preceding vehicle 1, andpossibly also other external factors such as road and weather condition,etc.

The second sensor device 4 is range sensor, such as a RADAR (radiodetection and ranging) sensor, or a LIDAR (Light detection and ranging)sensor. The second sensor device 4 is thus used to measure the distanceto preceding vehicles 1 within the operating range and operating angleof second sensor device 4. Based on information of absolute position andspeed of the host vehicle 2 received from a GPS-device 14, or adifferential GPS-device arranged on the host vehicle 2, the vehiclecontrol system 10 can determine absolute position and absolute speed ofpreceding vehicles 1 by fusing sensor information 20 received from thefirst and second sensor devices 3, 4. Sensor information fusion can beimplemented using several different well-known fusion algorithms, suchas a Kalman filter. Sensor information fusion may also be performed byembedded microcomputer systems arranged near to the first and secondsensor devices 3, 4, thus transmitting processed data, to the vehiclecontrol unit 10 relating, to relative or absolute position or speed ofpreceding vehicles 1, as well as their identity.

The host vehicle 2 may of course be provided with additional sensordevices for further improving the reliability of the determinedposition, speed and identity of preceding vehicles 1. For example, asecond image sensor arranged with a different viewpoint compared withthe first image sensor would allow stereoscopic vision of ahead of thehost vehicle 2, thus further improving range and position estimation ofpreceding vehicles 1.

Alternatively, or in combination with a second image sensor, anadditional range sensor, such as a RADAR or LIDAR sensor can be providedin the host vehicle 2 for improved measurement certainty.

The inventive method and arrangement need to uniquely recognise theidentity of the preceding vehicles 1 for comparing the identity of thepreceding vehicles 1 with data in a remote database system 5. Theidentity of preceding vehicles 1 can be in form of an identifier of alicense plate, a visual identifier of another type of unique marking, anelectronic identifier such as radio-frequency identification (RFID), inwhich case a further sensor device is required in form of a RFID readerarranged on the host vehicle 2. The identifier can be permanently ortemporarily attached to the preceding vehicle 1. Yet another option fordetermining a unique identity is to accurately estimate the position ofthe preceding vehicle 1, for example in terms of latitude and longitude,possibly also including additional preceding vehicle 1 attributes suchas speed, heading, driving lane, and type.

The remote database system 5 is a stationary database system managed bya supplier, and connectable to vehicles using, wireless communication 8,9, for example in form of wireless cellular radio network communication,such as GSM. The database system 5 comprises a database, which holdsdata of member vehicles of the database. Data of the database includes aunique identity of each vehicle of the database. This data can be in theform of an identifier of a license plate, an absolute position, or thelike, as mentioned above, hi case the identifier consists of orcomprises an absolute position, frequent update of the position isrequired to hold the database accurate and valid, for example every fiveseconds. Preferably, the timestamp of the update is also pan of thevehicle database to enable vehicle position estimation at each instantin combination with speed and heading of said vehicle. Continuouscommunication 8, 9 or on-request communication 8, 9 between membervehicles and database system 5 is possible. To register a non-membervehicle as a member to the database, a communication routine is set upfor managing the communication 8, 9 between the vehicle and the databasesystem 5, and connection data for establishing vehicle to vehiclecommunication 7 without database system routing can optionally also bestored in the database.

A main aspect of the invention is to establish a secure, reliable andhigh speed wireless communication channel 7, 8, 9 between the hostvehicle 2 and the preceding vehicles 1 that are identified by the hostvehicle 2 and being members of the database. Hence, simultaneouscommunication with more than one preceding vehicle 1 is possible beforeselection of a target vehicle to engage autonomous following of, for thepurpose of providing the operator 6 of the host vehicle 2 with thewidest possible choice of target vehicles.

A first possible implementation of such a communication channel 7, 8, 9between the host and target vehicles 1, 2 is based on said vehicle todatabase communication 8, 9, wherein data from the preceding, vehicle 1is transmitted to the host vehicle 2 via, the database system 5, andoppositely. This type of communication 8, 9 is thus configured as athree-part communication routed via the database system 5. The advantageof this type of implementation is low cost because no furtherinvestments are required, for any wireless point-to-point communicationbetween the host and preceding vehicle 1, 2, and simple establishment ofa communication channel 8, 9.

A second implementation of such a communication between the host andpreceding vehicles 1, 2 is based on setting up a direct, vehicle tovehicle communication 7, without routing over the database system. Theestablishment of such a vehicle to vehicle communication channel 7 isbased on connection information provided by the database system 5 to thehost and preceding vehicles 1, 2. The advantage of this type ofimplementation is potentially higher communication speed and increasedcommunication reliability because data does no longer need to betransmitted via the database system 5. There are many well-knowntechnical solutions available for providing a wireless vehicle tovehicle communication channel 7. A first solution is implemented bymeans of external cellular communication network, such as GSM, or adedicated short-range communication (DSRC) system. A second solution isimplemented by means of a direct wireless point-to-point communicationchannel 7 between the host and preceding vehicle 1, 2, wherein each ofsaid vehicles 1, 2 is provided with a suitable transceiver fortransmitting and receiving data directly between said transceivers ofsaid vehicles 1, 2. The direct communication channel 7 can be based onradio wave communication, such as millimetre wave radio link, or opticalcommunication, such as free-space optical links using infrared laserlight or LED. This alternative has the advantage of being independent ofan external cellular communication network, and having the potential ofvery high speed communication.

A third implementation of such communication can be based on acombination of communication with and without routing via the databasesystem 5, depending for example on the type of data transferred.

A human-machine interface H I 15 is provided between the vehicle controlsystem 10 and the operator 6 of the host vehicle 2 for informing theoperator 6 of the present status, as well as functioning as an obtainingpart for obtaining information required to enter and operate anautonomous following mode. For the purpose of entering said mode,information to the operator 6 is provided by an identifying device ofthe HMI 15 of the existence of preceding vehicles 1, as well as of thepossibility to select said preceding vehicles 1 as target vehicles forengaging autonomous following of. The HMI 15 is preferably implementedby means of a digital screen 16 that shows a realtime image of ahead ofthe host vehicle 2 based on information provided by the first sensordevice 3, as illustrated in FIG. 2. Information relating to selection ofa target vehicle, as well as setting a preferred range gap to the targetvehicle, can be inputted by the operator 6 using any type ofinput-device. Preferably, said input-device is implemented by arrangingsaid digital screen 16 as a touchscreen.

The possibility to select a target vehicle out of the preceding vehicles1 is dependent on the systems capability to first identify saidpreceding vehicles 1, and subsequently establishing a wireless datacommunication channel 7, 8, 9 with said preceding vehicles 1. Only aftersaid communication 7, 8, 9 have been established is it possible for theoperator 6 to select any preceding, vehicle 1 as target vehicle.

The status of preceding vehicles 1 can thus be divided in three levels:First level—not identified preceding vehicle 1; Second level—identifiedpreceding vehicle without established communication channel 7, 8, 9thereto; and third level—identified preceding vehicle 1 with establishedcommunication channel 7, 8, 9 thereto. In the present embodiment of theinvention as illustrated in FIG. 2, the third status level is indicatedto the operator 6 of the host vehicle 2 by displaying a frame 16 havinga first colour surrounding a preceding vehicle 1 in the digital screen16, the second status level is indicated by displaying a frame 16 havinga second colour surrounding said preceding vehicle, and the first statuslevel is indicated by the lack of any surrounding frame 16. Many otherconfigurations for showing selectable preceding vehicles 1 are of coursepossible within the scope of the invention.

Said preferred range gap between the host vehicle 2 and target vehicleis subsequently adopted as reference gap by said vehicle control system10 during operation of the autonomous following mode. Said range gap isset such that the range between said target vehicle and said hostvehicle 2 during engaged autonomous following mode at speeds above 50km/h, preferably above 70 km/h, is less than 30 metres, preferably lessthan 15 metres, and more preferably less than 5 metres. The minimumallowed range gap depends on at least speed of target vehicle andcommunication latency between target vehicle and host vehicle 2, and isselected to provide a certain safety level. With reduced target vehiclespeed, range gap can also be reduced with maintained safety level.Furthermore, with reduced communication latency, the range gap can alsobe reduced with maintained safety level. The operator 6 can of courseset a time gap instead of a range gap if desired.

Subsequent obtaining information of operator 6 selection of targetvehicle, the vehicle control system 10 takes control over at least themain power plant for vehicle forward propulsion, steering system, andbraking functions, such that the vehicle control system 10 can operatethe host vehicle 2 in an autonomous following mode. Control of thevehicle forward propulsion implies control of throttle valve positionand/or fuel injection, and control of the braking functions refers tovehicle de-acceleration achieved by standard friction brakes, motorbrake, exhaust brake, electric generators, and different types ofretarders, or the like.

To operate the host vehicle 2 in an autonomous following mode, thevehicle control system 10 receives information from the first and secondsensor devices 3, 4, the GPS 14, preferably in combination with digitalmaps, as well as driving information pertaining to the target vehicle 1via a wireless communication device 19 and the established communicationchannel 7, 8, 9. Said driving information can comprise speed,acceleration, braking actuation, braking pressure, engine data, targetdestination, cargo data and driving mode of the target vehicle.

Instead of a GPS-device 14, it is also possible to obtain a reasonableposition estimate of the host vehicle 2 using recorded route data incombination with an inertial navigation system, such as road inclinationsensors, gyros and/or accelerometers. Intercommunication between partsof the system of the host vehicle 1 is realized by means of a LAN or thelike.

The method for entering and operating the preceding vehicle autonomousfollowing mode will now be described. The first sensor device 3continuously sends image information to the digital screen 16 via thevehicle control system 10. Hence, the digital screen 16 displays animage of ahead of the host vehicle 3 to the operator 6.

In a first step, the first and second sensor devices 3, 4 registerpreceding vehicles 1 in front of the host vehicle 2, and transmit sensorinformation 20, such as range, angular position, possible license plateidentifier or other type of identifiers to the vehicle control system10. The vehicle control system 10 fuses sensor information 20 receivedfrom the first and second sensor devices 3, 4, and attempts to identifythe preceding vehicle 1. When a preceding vehicle 1 has been identified,optionally taking into account the position the host vehicle 2 using forexample a OPS-device 14, an enquiry is transmitted to the remotedatabase system 5 by means of a communication device 19 of the hostvehicle and a communication channel 9. This communication channel 9 canbe set up for each enquiry, or remain permanently operational dependingon the specific needs of the system. Furthermore, upon identification ofthe preceding vehicle 1, a red frame 17 appears around the identifiedpreceding vehicle 1 in the digital screen 16 as a status indication tothe operator 6 of the host vehicle 2 that the indicated preceding hasbeen identified by the vehicle control system 10.

The database system 5 subsequently compares the received identity of theregistered preceding vehicle 1 with vehicle data in the remote databasesystem 5. Depending in what type of identity is used by the inventivesystem, the database system 5 will compare identifiers of licenseplates, other visual or electronic, identifiers, absolute position ofvehicles, etc. Upon match, a communication channel 7, 8, 9 isestablished between the identified preceding vehicle 1 and the hostvehicle 2, which communication channel 7, 8, 9 is either routed via thedatabase system 5, or is established without routing via the databasesystem 5. Furthermore, upon establishment of a communication channel 7,8, 9 with the preceding vehicle, said red frame 17 turns into a greenframe 17 as a status indication to the operator 6 that the indicatedpreceding vehicle 1 now can be selected as target vehicle for enteringautonomous following of

Should the operator 6 want to engage autonomous following mode of apreceding vehicle 1 surrounded by a green frame 17 on the digital screen16, the operator 6 simply touches the digital touchscreen 6 within thedisplayed green frame 17 of said preceding vehicle 1 to select andconfirm that the vehicle control system 10 is commanded to take controlover propulsion, steering and braking function of the host vehicle 2,and to operate the host vehicle 2 in autonomous following mode havingthe selected preceding vehicle 1 as target vehicle.

The reference range gap to the preceding vehicle I can either bepredetermined and for example be dependent on speed and communicationlatency, or be set by the operator (upon request of the vehicle controlsystem 10 each time entering the autonomous following mode, for exampleby means of the digital screen 16.

To disengage autonomous following mode and return to operator drivingmore, the operator 6 can for example actuate any of the acceleratorpedal, brake pedal, or steering wheel.

It is possible that more than one preceding vehicle 1 is registered bythe inventive system simultaneously. Such a situation is illustrated inFIG. 2, where two preceding vehicles 1, one in each lane of the road 18,are displayed on the digital screen 16. The vehicle control system 10can preferably execute the different steps of the method for enteringand operating the autonomous following mode substantially simultaneouslyfor each of said two preceding vehicles 1. It is thus possible that theoperator 6 has the option of selecting a target vehicle out of severalselectable preceding vehicles 1.

As will be realised, the invention is capable of modification in variousobvious respects, all without departing from the scope of the appendedclaims.

Accordingly, the drawings and the description thereto are to be regardedas illustrative in nature, and not restrictive. Reference signsmentioned in the claims should not be seen as limiting the extent of thematter protected by the claims, and their sole function is to makeclaims easier to understand.

1. A method for entering a preceding vehicle autonomous following modecomprising the steps of: registering at least one preceding vehicle infront of a host vehicle by means of at least a first and a second sensordevice; identifying the at least one preceding vehicle; comparing the atleast one preceding vehicle with vehicle data in a remote databasesystem, and upon match establishing a communication channel between theat least one preceding vehicle and the host vehicle; identifying to anoperator of the host vehicle preceding vehicles with which thecommunication channel has been established; obtaining from the operatora selection of a target vehicle to engage following of; and engagingautonomous following mode of the target vehicle, wherein a vehiclecontrol system automatically controls at least the following three mainfunctions of the host vehicle: forward propulsion, steering, andbraking.
 2. The method according to claim 1, wherein the first sensordevice is an image sensor adapted for object detection identification,and where the second sensor device (4) is range sensor, such as a RADARor LIDAR device, that is adapted to measure at least the range to the atleast one preceding vehicle from the host vehicle.
 3. The methodaccording to claim 1, wherein the step of identifying the at least onepreceding vehicle comprises recognising an identifier of a license plateor other type of unique marking of the at least one preceding vehicle,or estimating a position of the at least one preceding vehicle, suchthat a unique identity of the at least one preceding vehicle can bedetermined.
 4. The method according to claim 3, wherein estimating aposition of the at least one preceding vehicle is based on at leastmeasured relative position thereof, and knowledge of at least positionof host vehicle, wherein at least the position of the host vehicle isprovided by means a GPS-device.
 5. The method according to claim 4,wherein at least the measured relative position and/or measured relativespeed is obtained by fusing information received from the at least firstand second sensor devices.
 6. The method according to claim 1, whereinthe remote database system is a stationary database system connected toat least one wireless communication device for establishingcommunication channels with vehicles registered in the database system,wherein the communication channels is based on wirelesstelecommunication.
 7. The method according to claim 1, wherein thedatabase system comprises a collection of vehicle data representing aplurality of unique vehicle identities, which vehicle data comprisesidentifiers of license plates or other type of unique vehicle markings,or position information provided by the vehicles.
 8. The methodaccording to claim 1, wherein the step of establishing a communicationchannel between the at least one preceding vehicle and the host vehicleis implemented by means of communication routing via the databasesystem, or by means of an external cellular communication withoutrouting via the database system, or by means of a direct wirelesspoint-to-point communication channel.
 9. The method according to claim1, wherein the step of identifying to the operator of the host vehiclepreceding vehicles with which the communication channel has beenestablished, is realized by means of a suitable human-machine interface,preferably in form of a digital screen displaying a real time image ofahead of the host vehicle, wherein status information is provided to theoperator indicating with which of the preceding vehicles thecommunication channel has been established.
 10. The method according toclaim 9, wherein the status information is realized by at least oneframe displayed on the digital screen and substantially surrounding thepreceding vehicles with which the communication channel is established.11. The method according to claim 10, wherein said the statusinformation is realized by at least on frame having at least a firstcolour and a second colour, wherein each of the preceding vehicles withwhich the communication channel has been established is indicated with aframe having first colour, and each of the registered vehicles withwhich no communication channel has been established is indicated with aframe having a second colour.
 12. The method according to claim 1,wherein the step of obtaining from the operator of the host vehicle atarget vehicle to engage following of comprises obtaining from theoperator selection information indicating, a unique preceding vehicle bymeans of an input device, which preferably is realised by implementingthe digital screen as a touch screen.
 13. The method according to claim1, further comprising the step of obtaining from the operator apreferred range gap between the host vehicle and the target vehicle,which preferred range gap is adopted as a reference gap by the vehiclecontrol system during operation of the autonomous following mode. 14.The method according to claim 13, wherein the range gap is set such thatthe range between the target vehicle and the host vehicle duringoperating autonomous following mode at speeds above 50 km/h, preferablyabove 70 km/h, is less than 30 metres, preferably less than 15 metres,and more preferably less than 5 metres.
 15. An arrangement for enteringand operating a preceding vehicle autonomous following mode, comprisingat least a first and a second sensor device for registering at least onepreceding vehicle in front of a host vehicle; a vehicle control systemfor identifying the at least one preceding vehicle; a remote databasesystem comprising vehicle data with which the at least one precedingvehicle is compared, such that a communication channel is establishedupon match between the at least one preceding vehicle and the hostvehicle; an identifying device for identifying to an operator of hostvehicle those preceding vehicles with which the communication channelhas been established; an obtaining part for obtaining from the operatora selection of a target vehicle to engage following of; and a vehiclecontrol system which controls at least the following three mainfunctions of the host vehicle: forward propulsion, steering, andbraking, for operation of the host vehicle in an autonomous followingmode.